Combustion mixture control



Juy 14,1931.

G. H. IRWIN 1,814,163 l COMBUSION MIXTURE CONTROLv Filed Aug. 11, 1928 2 sheets-sneer 1 July 14, 1931. G. H. IRWIN COMBUSTION MIXTURE CONTROL Filed Aug. ll,

Patented July 14, 1931 lPATENT OFFICE GEORGE H. IRWIN, OF CHICAGO, ILLINOIS COMBUSTION MIXTURE CONTROL l Application led August 11, 1928. Serial No. 298,954.

My invention relates to improved combustion mixture control for gas ired boilers or furnaces where natural or manufactured gas and air are `first properly proportioned and thoroughly mixed in a mixing device such as a fan or blower to form a complete and perfect combustion mixture which is delivered to the lire box of the boiler or furnace withf out further admixture' of air. y The fan is connected to receive gas from a supply main and has air inlets of adequate area r sufiicient air intakev during normal range of gas pressure in the main. Sometimes the gas pressure may materially diminish, and it may be necessary tocorrespondingly diminish the air inlet to the fan in order to maintain the proper proportion of gas and air and eiicientcombustion mixture.

The important object of my invention is to automatically adjust and control the air supply to the fan in accordance with the variation in gas pressure and thereby to assure at all times delivery of a perfect complete combustion mixture by the fan.

Another object is to provide improved arrangement for assuring safety against gas leak or back liring.

Referring to the drawings Figure 1 is a plan view of the combustion mixture supplying and controlling apparatus applied to a boiler which is shown in horizontal section.

Figure 2 is a front elevational view of the apparatus and boiler, partly in section on plane 2-Fig. 1.

' Figure 3 is a side elevation of the apparatus and boiler, and C Figure 4 is an enlarged sectional View on plane 4 4 Fig. 3;

The irebox A1 of the boiler 2 has the combustion mixture inlet opening 3, but is otherwise sealed against the entrance of air. A bracket structure 4 is secured to the boiler at the inlet opening 3 by bolts 5, and the flange.v 6 4on the burner structure 7 is detachably se\ cured to the bracket as-by bolts 8 with its nozzle 9-projecting into the opening to vdirect the burning combustion mixture or iiame into the irebox or furnace. v

.5 On top of the supporting bracket are mounted a motor 10 and the housing 11 for centrifugally operated mechanism for automatically admitting or shutting off the gas flow to the fan housing 12 secured to and supported by the housing 11. In the arrangement shown, the fan rotor 13 is secured to the shaft 14 which is journaled on and extends through the housing 11 and is connected with the motor by a coupling 15.

The gas supply to the fan is .by Way of pipe 16, in which maybe interposed a main shut-olf valve 17, the pipe connecting with the housing 18 for the automatic shut-ofi valve 19, the gas flowing through the valve port 20 into the valve chamber 21 and from there through passageways 22 and 23 to the fan housing at the axis thereof. A. regulator or setting valve 24 cooperates Withthe' passage 22 to determine the volume of gas flow to the fan under normal gas pressure. The automatic opening and shut-off valve 19 for the gas flow is connected by the stein structure 25 with the outer end of a lever 26 fulcrumed at 26 Within the housing 11 and connecting at its linner end with the collar 27 surrounding the hub 28 on the shaft 14:.

This hub rotates with, but is slidable on, the

shaft and is connected by links 29"with the centrifugal weights30 which swing on the hub 31 secured to the shaft. A compression spring 32 encircles the shaft between the hubs and resists movement of the hub 28 and tends to hold the hub and lever in position to cause the valve 19 to close the valve port 20.

Air enters the fan housing atits axis and its tangential outlet 33 is connected by the fitting 34 with the inlet end 35 of the burner x structure to deliver the thoroughly mixed gas and air to the burner nozzle.

The fan housing has preferably permauently open air ports 36 Whose area is ad.- justed or set by means of a shutter 37. These ports and shutter are preferably located at the inner side of the fan housing to be suiiiciently inaccessible to discourage tampering therewith by unskilled persons. ,"At the outer side of the fan housing are," the auxiliary air ports 38 controlled by the rotary shutter plate 39-having ports 40. The

plate shown is circular and rotateson and is held to its seat on the fan housing by the post 41. The annularshoulder 42 surrounding the plate will assist in aliningand guiding it.

rlhe shutter 37 is permanently adjusted and set so that the continuous air inlet area together with the auxiliary air inlet area when the auxiliary ports 38 re wide open will be suiiicient to furnish ad quate air sup-Y ly for the volume of gas delivered to the an past the regulator valve 24 during normal range of gas pressure in the gas main and supply pipe 16. However, the gas-pressure may at times drop considerably below normal and the air volume must then beicorrespondingly reduced in order to maintain the eiiiciency of the combustion mixture delivered by the fan. An important feature of myinvention is to accomplish such @air regulation automatically in accordance with the reduction in gas pressure, and by the reduced air inlet to increase the` suction effort of the fan on the gas main so that the fan will tend to draw suiiicient gas from the main in spite of-diminishing gas pressure.

Theair lregulation is accomplished by a diaphragm 43 operating the auxiliary air shutter 39. This dia hragm may be of' leather or other suita le material and is clamped at its edge between the housing -walls 44 and 45 to form upper and lower vchambers 4 and 47. A piston 48 is secured.

to the diap agm between the shoulder 49 and washer 50 on the piston rod 51, this rod passing through the tubular lug 52 on'the wall 45 and being connected by link 53 with the crank pin 54 on-th'e auxiliary lair shutter 39. The diaphragm structure may be supported in anyi convenient position. As shown it is mounted by means of its lug on the side of the fan housing.

The upper wall 44 has the gas inlet 55 from which a pipe 56 extends to the gas main 16 so that the chamber 46 above the diaphragm is subjected to the gas pressure. When the pressure is normal the diaphragm will be held down against the pressure of the spring 57A within the lug 52 between the piston 48 and the washer 58 seating on the ledge 59. In this position of the diaphragm the shutter 39 has its ports 40 in full registration with the auxiliary ports 38 for maximum auxiliary air inlet.V When the pres-` the fan is restricted to the air inlets or ports 36 and the suction effort of the fan is greatly increased and exerted on the gas supply main to draw gastherefrom so long as any gas is available therein. With return of the gas pressure to normal the diaphragm will reopen the auxiliary shutter for the restoration of the air supply to normal.

In the lower end of the lug 52 soft packing material 60 surrounds the piston rod .and is held compressed around the rod by a spring 61 encircling the rod between the washer 58 and the washer 62 over the acking. This spring' is comparatively ight and does not interferel with the operation' of the piston spring 57. The packing is kept in proper condition by the light springwithout undue resistance to easy operation L of the piston rod and being inaccessible it cannot be tampered with. a

Tovent the chamber 47 below the diaphragm as the diaphragm operates a vent pipe 63 leads` therefrom and is preferably connected with the smoke box or uptake of the boiler so that in case the diaphragm should at any time become ruptured from over pressure or Wear, the gas leaking therethrough will flow through the vent and up the stack or chimney thus eliminating the danger and damage to the building or inmates.

The. burner shown has the annular noz-` zle 9 which receives the combustion mixture fromthe burner inlet end 35, the outer wall of thev nozzle having thegasl ports 64 for directing the mixture into the fire box or furnace. A pilot iame maybe applied in the opening 65 surrounded by the' nozzle but preferably a spark plug (not shown) is inserted and-connected with an electrical ignition circuit.` Y

When the motor is not o erating and the fan is at rest, the centri gal mechaf nism holds the gas valve 19 closed.` When the motor is put intoA operation the valve is opened for the flow of gas to the operating fan. Preferably the spring32 is su'iicient- 1y stili to delay the centrifugal mechanism from opening the valve until the motor and fan approach full speed; and to cause the valve to close .rapidly when the motor cir-y cuit is opened .so that the momentum of the motor, before it comes to rest,will continue to rotate the fan for a sucient time to clear the fan housing and .burner of any gas vor combustion mixture, thereby insuring safety.l I' v By delaying the opening of the^gas valve to permit. the motor to acquire nearly maximum speed with corresponding speed and pressure of air throughthe burnerV before gasl is admitted to the fan, tendency to back firing will be eliminated. v

To "further guard against back firing, a

check valve 66 is applied in the passage from the fan to the, burner.

I do not desire to be limited to the exact structure and arrangement shown, as

' u, changes and modications may be made 1 without departing from the scope of my invention. e.

I claim vas `follows:-

In a combustion system, the combination of a boiler, a blower for receiving and mixing air and natural or manufactured gas to produce a combustion mixture, a source of gas supply connected, with the blower intake, and air inlet at the blower intake, lb a valve for'said inlet, a diaphragm structure comprising a housing and a diaphragm therein, said gas lsupply source being connected with said housing at one side of' said diaphragm whereby said diaphragm is sub- 20 jected to the gas pressure, spring means resisting movement of the diaphragm by the gasA pressure, said valve being connected with said diaphragm to be moved thereby to regulate the air inlet in accordance with 25 the gas pressure variation whereby to maintain a'ixed proportion of air and gas sup- `ply to the blower, a burner connected with the blower outlet to receive the combustion mixture, and a vent vconnection from the so diaphragm housing to a combustion pas.

sage of said boiler for the 'escape of leakage gas in case the Vdiaphragm should leak or become ruptured. l f In witness whereof, I have hereunto sub- '35 scribed my name this 9th day of August 1928. GEORGE H. IRWIN. 

